linux-kernel - Re: [PATCH 1/3] workqueue: Convert for_each

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Date:   Sun, 11 Aug 2019 18:12:32 -0400
From:   Joel Fernandes <joel@...lfernandes.org>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jonathan Corbet <corbet@....net>,
        Josh Triplett <josh@...htriplett.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>, rcu <rcu@...r.kernel.org>,
        Steven Rostedt <rostedt@...dmis.org>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 1/3] workqueue: Convert for_each_wq to use built-in list
 check (v2)

On Sun, Aug 11, 2019 at 6:11 PM Joel Fernandes (Google)
<joel@...lfernandes.org> wrote:
>
> list_for_each_entry_rcu now has support to check for RCU reader sections
> as well as lock. Just use the support in it, instead of explicitly
> checking in the caller.
>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>

Tejun,
Could you please Ack this patch? I have resent it here.

Thank you,
- Joel


> ---
>  kernel/workqueue.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 601d61150b65..e882477ebf6e 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -364,11 +364,6 @@ static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
>                          !lockdep_is_held(&wq_pool_mutex),              \
>                          "RCU or wq_pool_mutex should be held")
>
> -#define assert_rcu_or_wq_mutex(wq)                                     \
> -       RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&                       \
> -                        !lockdep_is_held(&wq->mutex),                  \
> -                        "RCU or wq->mutex should be held")
> -
>  #define assert_rcu_or_wq_mutex_or_pool_mutex(wq)                       \
>         RCU_LOCKDEP_WARN(!rcu_read_lock_held() &&                       \
>                          !lockdep_is_held(&wq->mutex) &&                \
> @@ -425,9 +420,8 @@ static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
>   * ignored.
>   */
>  #define for_each_pwq(pwq, wq)                                          \
> -       list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node)          \
> -               if (({ assert_rcu_or_wq_mutex(wq); false; })) { }       \
> -               else
> +       list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node,          \
> +                                lock_is_held(&(wq->mutex).dep_map))
>
>  #ifdef CONFIG_DEBUG_OBJECTS_WORK
>
> --
> 2.23.0.rc1.153.gdeed80330f-goog
>